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County · code 19099

Jasper CountyIowa

Jasper County is a county in Iowa with its seat in Newton. It was formed on January 13, 1846, and covers 730 square miles.

  • Founded1846
  • County seatNewton
  • Named forWilliam Jasper
  • Land area730 sq mi + 2.5 sq mi water
  • Population37,813 2020 Census
  • Parcels mapped29,928 checked 16 October 2026
Open the free map Click any parcel in Jasper County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

PolkPoweshiek Newton Census outline · seat marked

Where it is

Jasper on the map of Iowa

Iowa has 99 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adair CountyAdams CountyAllamakee CountyAppanoose CountyAudubon CountyBenton CountyBlack Hawk CountyBoone CountyBremer CountyBuchanan CountyBuena Vista CountyButler CountyCalhoun CountyCarroll CountyCass CountyCedar CountyCerro Gordo CountyCherokee CountyChickasaw CountyClarke CountyClay CountyClayton CountyClinton CountyCrawford CountyDallas CountyDavis CountyDecatur CountyDelaware CountyDes Moines CountyDickinson CountyDubuque CountyEmmet CountyFayette CountyFloyd CountyFranklin CountyFremont CountyGreene CountyGrundy CountyGuthrie CountyHamilton CountyHancock CountyHardin CountyHarrison CountyHenry CountyHoward CountyHumboldt CountyIda CountyIowa CountyJackson CountyJefferson CountyJohnson CountyJones CountyKeokuk CountyKossuth CountyLee CountyLinn CountyLouisa CountyLucas CountyLyon CountyMadison CountyMahaska CountyMarion CountyMarshall CountyMills CountyMitchell CountyMonona CountyMonroe CountyMontgomery CountyMuscatine CountyO'Brien CountyOsceola CountyPage CountyPalo Alto CountyPlymouth CountyPocahontas CountyPolk CountyPottawattamie CountyPoweshiek CountyRinggold CountySac CountyScott CountyShelby CountySioux CountyStory CountyTama CountyTaylor CountyUnion CountyVan Buren CountyWapello CountyWarren CountyWashington CountyWayne CountyWebster CountyWinnebago CountyWinneshiek CountyWoodbury CountyWorth CountyWright CountyJasper County Jasper
Counties of Iowa · Jasper highlighted

History

Formed in 1846 from Mahaska County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Jasper County was created by Iowa Territory from Non-County Area 8 and land from Mahaska and Polk counties, though it was not fully organized at first. Marshall County was temporarily attached to Jasper for election, revenue, and judicial purposes when Jasper was fully organized in March 1846, but Marshall became fully organized and detached in October 1849. When Iowa became a state in December 1846, Jasper County became an official Iowa county.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

  1. 1846
    Jasper County created Jasper created by Iowa Territory from Non-County Area 8 attached to Mahaska; Jasper not fully organized, not attached.
    from Mahaska
    · Iowa Terr. Laws 1845-1846, ch. 82, sec. 6/p. 74
  2. 1846
    Gained territory Jasper gained from Polk.
    from Polk
    · Iowa Terr. Laws 1845-1846, ch. 83, secs. 1-3/pp. 75-76
  3. 1846
    Changed Jasper fully organized; Marshall attached to Jasper "for election, revenue, and judicial purposes".
    Marshall
    · Iowa Terr. Laws 1845-1846, ch. 101, secs. 1, 11-12/pp. 92-95
  4. 1846
    Became part of Iowa Jasper became an Iowa county when the state of Iowa was created from Iowa Territory. · U.S. Stat., vol. 9, ch. 1[1847]/p. 117
  5. 1849
    Changed Marshall fully organized, detached from Jasper.
    Marshall
    · Swisher, "Organization of Counties," 574-575

Land and parcels

What the maps cover in Jasper

Who publishes each layer, how good it is, and when we last checked.

Official
from the office that keeps the record
Good enough
a reliable statewide or national copy
Fallback
a guide only; check the official record
Missing
nothing public found yet

People and land

Jasper by the Census

Population
37,813 2020 Census count
Housing units
16,132 2020 Census count
Land area
730 square miles
Water area
2.5 square miles
People per sq mi
52 population ÷ land area

Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.

Rules and offices

Jasper County's official site

We have found the county's site but not its offices yet; start there.

County government

See your own lot on these maps

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Questions

Common questions about Jasper County

When was Jasper County founded?
Jasper County was founded in 1846, formed from Mahaska County, and named after William Jasper.
What is the county seat of Jasper County?
The county seat of Jasper County is Newton.
Is there an online parcel map for Jasper County?
Yes. A public source publishes a parcel map of 29,928 parcels, rated fallback here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Jasper County's boundary or name changed?
Jasper County was created in 1846 from Mahaska County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Marshall County and Polk County.
Is my lot in a flood zone?
We do not have flood maps for Jasper County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby

Counties next door